Right below our feet is a large ball of energy slowly cooling into outer space. This cooling of our planet significantly impacts our climate, plate tectonics, and magnetic field generation in the core. But what determines the evolution of the Earth & other planet interiors? What are the properties of mantle and core minerals and alloys? I use first principles to model and understand the evolution of the deep interiors of the Earth and other planets in our solar system and beyond.

Interior Evolution

dynamics and high-pressure properties


  1. Bullet HIGHLIGHTS

  2. BulletMelting temperature, thermal conductivity, and viscosity for mantle rock might be much larger than previously assumed - with strong implications for the Earth’s evolution and for the structure and evolution of rocky exoplanets: I compute state of the art viscosity, thermal expansivity, and thermal conductivity (phonon, radiative, and electronic) for the Earth’s mantle and for super-Earths from first principles. Total thermal conductivity increases strongly with depth. My viscosity model perfectly satisfies the current viscosity constraints for the Earth. Computed melting temperatures are indirectly supported by melting experiments for MgO (McWilliams et al. 2012, Science).


  1. BulletEarth’s thermal history needs a revision: Especially the interior conditions of the early Earth might have been much hotter than previously assumed - with strong implications for volcanism, the water cycle, and plate tectonics: Assuming full mantle convection (versus layered convection), I can only reproduce the inner core radius constraint for large activation volumes. Pressure-independent models do not satisfy the viscosity constraints by many orders of magnitude. They can only then satisfy the inner core radius constraint if there is either layered mantle or stagnant lid convection throughout most of the Earth’s history. New results on the validity of previous thermal evolution models (Stamenkovic and Breuer 2014, Stamenkovic 2014) additionally support the findings that early Earth heat flow has been overestimated (see as well Tectonics).


  1. BulletInitial lower mantle temperature conditions control the thermal evolution of massive planets. Steady state models do not suffice: Initially molten super-Earths have a hot super-adiabatic temperature profile. Assuming interior temperatures from literature, the lowermost mantle would be stagnant. Hence, super-Earths might be much hotter than we think. Steady-state calculation are not sufficient to show this behavior, as cooling takes many billion years (even when forming molten). Ineffective lower mantle cooling impacts dynamo action & plate tectonics. Shorter volcanic activity on super-Earths. Problems for climate regulation. Problems for differentiation of rocky super-Earths.


  1. Bullet FURTHER READING

  2. BulletStamenković, V., Höink, T., Lenardic, T., 2016. The importance of temporal stress variation for the initiation of plate tectonics. JGR Planets, 121, 1–20, doi:10.1002/2016JE004994.

  3. BulletStamenković, V., Seager, S., 2016. Emerging possibilities and insuperable limitations of exogeodynamics: the example of plate tectonics. The Astrophysical Journal, 825, 78-95. Stamenković, V., Breuer, D., 2014. The tectonic mode of rocky planets, Part 1: driving factors, models & parameters. Icarus 234, 174-193.

  4. BulletStamenković, V., Noack, L., Breuer, D., Spohn, T., 2012. The influence of pressure-dependent viscosity on the thermal evolution of super-Earths. The Astrophysical Journal, 748, 41-63.

  5. BulletStamenković, V., Breuer, D., Spohn, T., 2011. Thermal and transport properties of mantle rock at high pressure: applications to super-Earths. Icarus, 216, 572–596.

  6. BulletStamenković, V., Frank, S., 2011 & 2015. Rheology of planetary interiors. In: Gargaud, M., et al., (Eds.), Encyclopedia of Astrobiology, Part 19. Springer, 1452-1455.

Mantle Viscosity for pv, MgO is strongly pressure-dependent with great implications for the thermal evolution of the Earth and super-Earths: yellow area indicates the observed viscosity profile of the Earth (Mitrovica and Forte, 2004). a) pv viscosity profiles for Earth along our reference geotherm: pressure- and temperature-dependent (dashed blue), non-pressure-dependent (dashed gray). b) MgO viscosity profiles for Earth along our reference geotherm (black lines with pink shaded uncertainty zone) and pv (gray line). (c,d) MgSiO3 pv viscosity as a function of pressure using the geotherm according to Stacey and Davis (2004) with a constant grain size of 1 mm (dashed line) and c) with varying grain size (dotted line) and d) with an alternative geotherm (Da Silva et al., 2000), which is adiabatic for pressures below ~85GPa (with a potential temperature of 1600K), but then increases linearly at larger pressures towards 3700K at the Earth’s CMB (solid line). Large viscosities ALONG AN ADIABAT for super-Earths indicating that super-Earths are hotter than previously assumed: (e) for pressures relevant to super-Earths: Viscosity along reference adiabat for MgSiO₃ pv (blue) in comparison to a viscosity without the inclusion of pressure effects (gray). This indicates that the thermal evolution of super-Earths is fundamentally different from the Earth, and that they remain hotter for much longer.

b)

a)

Large Thermal Conductivities reduce the convective vigor in the lower mantle: undisturbed radiative (dashed black), effective radiative (solid black), electronic (dotted black), total non-phonon (effective radiative + electronic) (dash-dotted black), phonon for an Earth-like MgSiO₃-perovskite-MgO-composite (gray dashed), and finally the total thermal conductivity (effective radiative + electronic + phonon) (solid yellow) with pressure: a) for Earth along the reference geotherm, for super-Earths b) along the reference adiabat, and d) along the pv reference melting profile. c) is non-phonon along temperature only.

Thermal Evolution Constraints for Earth Demand a Pressure-Dependent Viscosity: the interior temperature evolution for our Earth model in a stagnant lid (SL) and a plate tectonics regime (PT) with no effective activation volume (and with the activation volume being 2.5cm³/mol). In solid black (red) the CMB temperature Tc; in dash-dotted black (red) Tb, the temperature at the upper border of the lower mantle conductive zone; in solid gray (light red) Tm, the upper mantle temperature; and in dash-dotted gray (light red) is Tl, corresponding to the temperature at the base of the stagnant lid for the SL regime or to the surface temperature Ts=290K for the PT regime.

c)

d)

e)

Reduced convective vigor in the lower mantle for super-Earths: 2D simulation results for a 5 Earth mass super-Earth with Earth-like composition and structure, Tc(0)=5100, ηref=1022Pas and activation volumes~2.5cm3/mol for a standard initial thermal profile at the peak of convection around t=7.5Gyr. a) the 2D temperature [K], b) the convective velocities [cmyr-1], and c) the regions with the Peclet number smaller 1 (black), between 1 and 100 (red), and above 100 (white) - indicating stagnant, sluggish, and effectively convecting zones, respectively. The central gray-filled circle is the planet's core. NOTE: assuming planets that form molten, we do obtain full mantle convection, but the lower mantle of super-Earths remains sluggishly convecting.

All Right Reserved, 2016 Vlada Stamenkovic.